Wearable Pulsebeat Measurement Using Thermal Detection

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Solution Overview

Problem

Existing pulsebeat measurement apparatuses face issues such as discomfort due to electrode contact, limited durability, high power consumption, and difficulty in measuring pulsebeats through clothing or tattoos, which hinder continuous and accurate monitoring.

Innovation Solution

A wearable pulsebeat measurement apparatus that detects temperature changes caused by pulsations using a temperature sensor, incorporating a heat absorber to prevent thermal equilibrium and reduce power consumption, allowing for downsized and continuous pulsebeat measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the pulsebeat measurement apparatus is downsized, then power consumption is reduced and portability is improved, but the total heat capacity becomes small causing rapid thermal equilibrium and loss of detection accuracy

Engineering Contradiction:

Improvepower consumptionVSAvoidtemperature change detection accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent introduces a heat absorber that changes the thermal parameters of the measurement system. By adding a component with high heat capacity (the heat absorber), the system maintains low power consumption while preventing rapid thermal equilibrium, thus preserving temperature change detection accuracy despite downsizing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The heat absorber acts as an intermediary between the temperature sensor and the external environment. It mediates the thermal interaction by absorbing excess heat and preventing the sensor from rapidly reaching thermal equilibrium with the body, thereby maintaining detection sensitivity in a downsized apparatus.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If electrodes are used for pulsebeat measurement, then measurement accuracy is improved, but user comfort deteriorates due to tight contact requirements and restraint feelings

Engineering Contradiction:

Improveheart beat measurement accuracyVSAvoiduser comfort

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the mechanical contact-based electrode system with a thermal field-based temperature sensor system. Instead of requiring tight mechanical contact between electrodes and skin for electrical signal detection, the system uses temperature sensors that detect thermal changes caused by blood flow, thereby eliminating the discomfort associated with electrode contact while maintaining measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If light-based photoplethysmography is used, then non-contact measurement is achieved, but power consumption increases making continuous measurement impossible for wearable devices

Engineering Contradiction:

Improvenon-contact measurement capabilityVSAvoidlight emitting element power consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent substitutes the optical measurement system (light emitting elements and photodetectors) with a thermal measurement system using temperature sensors. This replacement dramatically reduces power consumption since passive temperature sensing requires minimal energy compared to active light emission, enabling continuous measurement in battery-powered wearable devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If light-based measurement is used, then pulsebeat can be detected through blood flow changes, but tattoos and coloring matters block light preventing appropriate reflected light capture

Engineering Contradiction:

Improvepulsebeat detection capabilityVSAvoidmeasurement reliability through clothing and tattoos

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces optical detection with thermal detection. Temperature sensors measure heat changes caused by blood flow pulsations rather than detecting reflected light. This substitution eliminates the problem of light blockage by tattoos and clothing, as thermal conduction through these materials is sufficient for detection, thereby improving adaptability and measurement reliability across different user conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate and continuous pulsebeat measurement with low power consumption, reducing discomfort and overcoming limitations of previous technologies by using a temperature sensor and heat absorber to maintain detection accuracy.

Implementation Method 1

a heat absorber configured to absorb heat of the first temperature detector

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 2

detecting a small change in temperature caused by a pulsation using a temperature sensor that detects the temperature on a contact surface with the human body

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10952626B2Pulsebeat measurement apparatus

Publication Date: 2021.03.23 KDDI CORP

AI summary

There is provided a pulsebeat measurement apparatus. The pulsebeat measurement apparatus includes a first temperature detector configured to detect a temperature of a human body, a specifying unit configured to specify a period of a temperature change caused by a pulsation of the human body based on the detected temperature, a pulsebeat measurement unit configured to measure a pulsebeat of the human body based on the specified period of the temperature change, and a heat absorber configured to absorb heat of the first temperature detector.